Optical properties of Cr3+ and Nd3+ in singly- and doubly-doped barium-indium-gallium-based fluoride glass investigated by time-resolved laser spectroscopy

Abstract
The optical properties of Cr3+, Nd3+, and Cr3+:Nd3+doped fluoride glass (30BaF2 18InF3 12GaF3 20ZnF2 10YF3 6ThF4 4ZrF4) have been investigated in the 4.2–300-K temperature range at several concentrations by using steady-state and time-resolved laser spectroscopy. The luminescence of trivalent chromium in singly-doped glass shows a strong thermal quenching and can be analyzed on the basis of two broad statistical site distributions. The luminescence quenching of the 4 F3/2 4 I11/2 laser transition of Nd3+ in singly-doped glass has been studied by investigating the thermal and concentration dependence of lifetimes. A T3 dependence for the nonradiative Nd3+ Nd3+ relaxation has been found in the 15–100-K temperature range at high Nd3+ concentrations, which is in agreement with a two-site nonresonant process. Cr3+-to-Nd3+ radiative and nonradiative energy transfer in codoped glass has been demonstrated from the emission spectra and the decrease of Cr3+ fluorescence lifetimes. The comparison between the time-resolved emission spectra of